The disclosures herein related generally to orthopedic implants and more particularly to an intramedullary nail.
There is a need for a xe2x80x9climb salvagexe2x80x9d method for treating metastatic tumor patients who had either suffered from a fractured limb, were in danger of suffering from a fractured limb due to voids in the bone structure, or were in need of internal limb stabilization resulting from actual or pending pathologic fracture of a limb. One common treatment described in the literature for these conditions is to retrograde fill the intramedullary (I-M) canal of the bone with bone cement and insert an I-M nail, bridging the defect, before the bone cement hardens. The reason for using a standard design I-M nail with cement is to provide stabilization and reinforce the limb around the void, deficient bone, or fracture site in order to prevent further deterioration. Without the use of cement for patients with these conditions, there is likely to be motion at the fracture site resulting in instability.
A common problem with this technique is that the I-M nail becomes lodged in the I-M canal before reaching full insertion. This is commonly the result of one or more causes such as: 1) the I-M rod selected becomes impinged at the fracture or bony defect site of the I-M canal; 2) most bones in the body have an anatomic bow (in one or more axis) that effectively reduces the diameter of the I-M canal through which a straight or non-flexible rod can pass without becoming immovably lodged prior to reaching the desired depth; and 3) due to a combination of the aforementioned conditions, the bone cement begins to harden before insertion of the rod is complete, thus preventing final seating of the device.
Another consideration is the application of an I-M rod as either a prophylactic treatment for the prevention of fracture or corrective trauma surgery for a long bone fracture for patients suffering front osteoporosis. It is known from literature that patients suffering from advanced stages of osteoporosis are more likely to fracture major bones sustained from simple trauma such as falling down. In such cases, surgeons may elect to use an I-M rod along with other stabilization techniques (i.e.: casting and/or cross-pinning) to achieve stabilization during healing. A device, used without bone cement, could serve this purpose, providing the same benefits to the surgeon as described in items 1 and 2 above. If needed, the device could still be removed at a later date.
Some of the known devices used for purposes mentioned above include U.S. Pat. No. 4,457,301 which describes an intramedullary multiple pin device for fixing fractures in the middle portion (diaphysis) of long bones. The multiple pins are resilient and held in a desired special arrangement by a flexible plastic core element.
U.S. Pat. No. 5,116,335 discloses an intramedullary device for use in internal fixation of a fracture transverse to the longitudinal axis of a long bone which includes a substantially rigid center rod having a plurality of longitudinal slots extending along the length thereof. One of a plurality of generally flexible outer rods is received and retained within one of the longitudinal slots and thereby extends outwardly from the center rod. Each outer rod has a retention section angulated from the longitudinal axis of the long bone which penetrates through and is retained by the cancellous bone thereby stabilizing the fracture at the distal and proximal ends of the long bone. In order to install the intramedullary device within the endosteal canal, each end of the generally flexible outer rods are coupled to one of a plurality of extension rods of an installation device. The generally rigid center rod is introduced through the central opening of the installation device and thus extends into the endosteal canal. As the center rod is moved into the endosteal canal, each of the outer rods is slidably engaged into one of the plurality of longitudinal slots of the center rod. This movement forces the cutting edge of each outer rod to penetrate through the cancellous bone and allows the retention section of the outer rods to be retained within the cancellous bone thereby stabilizing the fracture of the long bone.
In U.S. Pat. No. 5,135,527, an insert member for use in an impact hole leading into a medullary canal of a bone for treating a fracture by insertion of at least one bone nail into the medullary canal is disclosed. The insert member has a guide channel for receiving the proximal end of the bone nail, lateral openings and a pin for fixing the insert member in the impact hole, and a closure member for the proximal end of the guide channel. The closure member includes an abutment for the proximal end of the bone nail which allows limited reverse movement of the proximal end of the bone nail within the guide channel. The abutment may be a separate member attached to the closure member by a spring or the abutment may be a shaped projection extending forwardly from the closure member.
U.S. Pat. No. 5,281,225 discloses an intramedullary pin with a self-locking end for metadiaphyseal fractures, constituted by a proximal stub provided with means for fixing to the cortices; the ends of at least two curved and elastically deformable stems are axially rigidly associated with the stub, and the stems are adapted to expand elastically and to press with their tips the walls of the bone from the inside of the medullary canal.
Therefore, what is needed is a flexible intramedullary nail that allows for easier navigation through anatomic bows of the I-M canal during insertion, that can be piloted during trial insertion and final insertion, that allows for easy extrusion of bone cement into the body of the nail, and that can be used for stabilization in non-cemented applications.
One embodiment, accordingly, provides a flexible intramedullary nail which reduces resistance to penetration within the intramedullary canal, which can be used with or without bone cement, and which meets the anatomic requirements of various bones in the human skeleton. To this end, an orthopedic implant includes a first end cap, a second end cap spaced apart from the first end cap, and a plurality of elongated flexible members interconnecting the first end cap and the second end cap.
A principal advantage of this embodiment is that the xe2x80x9cbirdcage configuration of the implant device is variably flexible for easier insertion through the anatomic bows of the intramedullary canal. The device may be varied in length, diameter and stiffness, and may be used with or without bone cement.